the stated signs may be misleading, though, yes, it certainly is a steep grade, but RVs of all types and sizes make it up to the campground ... so, obviously, it's not 'too' steep, but it's just not the normal grade you'd expect just to get up to a campground.
I worry more about the descent down when leaving, as your brakes will be taking a lot of weight and pressure that they are not accustomed to. Just take it slow.
Also, realize that there is a very hard left and UPHILL 'switch back' turn within the campground - your site may be before that, but chances are you'll have to maneuver it regardless because the campground is simply a 'loop' road, whether you encounter it getting to your site, or when leaving.
These are the types of campgrounds and RVing situations where you can share stories about later - it's worth the trip, even if it creates some apprehension...
been there in our 35' diesel pusher pulling our tow car... and it's not just 1/4 mile, more like at least a mile from the check in point to the campground itself... much, yes, is very steep.
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
100,000+mi since '14 - US, Alaska, Canada - Hiawassee, GA! (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )